CHAPTER 1
INTRODUCTION
1.1
OBJECTIVE
The primary object of this report is to present the results of measurements of high-
resolution spectra photographed for the Mike and King shots at Operation Ivy and to compare
these results with similar data from previous operations.
1.2
BACKGROUND
Optical spectra at dispersions ranging from 2.5 A/mm to 8.3 A/mm have been photot
graphed for most of the explosions at Operations Greenhouse, Buster-Jangle, Tumbler-Snapper,
and Ivy. The wavelength region covered is from about 3000 A, where the spectrum is cut off by
some absorbing process, to an instrumental limit near 7800 A. The spectrograms vary in exposure time and wavelength coverage. They also vary in the time during the life of the fireball
at which the exposure was made. Table 1.1 gives information pertinent to the shots discussed
in this report. It includes for each shot the yield of the weapon in kilotons of TNT, the spectral
region photographed, the spectral region measured, the time limits of the exposure, and the
prominent atoms and molecules observed in the spectra.
In most of the spectra considered here, the exposure at a particular wavelength is the result of the integration of light on a photographic plate over a relatively long period of time and
from a wide region of space. The degree of space and of time integration is determined by the
exposure technique used.
The bomb spectra which have been photographed always show a continuous background, as
in the case of the photosphere of the sun. This serves as a background for absorption spectra
due to excitation of certain atoms and molecules near the surface of the fireball. In some
Cases the emission spectra of certain atoms and molecules have been obtained.
This report includes a table of the wavelengths and the estimated strengths of the lines
and bands observed between 3000 and 5000 A on someof the spectrographic plates obtained at
Greenhouse, Buster-Jangle, Tumbler-Snapper, and {vy (see Appendix A).
Most of the measured wavelengths have been identified as to the atomic or molecular
agents responsible. The intensity estimates are included because intensities can give indications of the amount of an agent present and the degree of its excitation.
1.3
THEORY
In general, an electronic molecular spectrum can be either of a broad continuous nature
or have structure, i.e., consist of sharp rotational linea, or bands which may or may not show
a resolved rotational structure. A spectrum which inherently consists of sharp separated
a
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a